This is a simple method I used to
copy an entire disk from one machine to another. I wanted
to do a hardware upgrade, with as little down-time as
possible, so I copied the entire root filesystem from one
machine to another.

You need the netpipes package,
which comes standard with Slakware. If you don't have it, get it from
sunsite.

On the existing machine, type (as
root)

# faucet 1234 -out tar -cvf - /

On the new machine, boot using an
existing installation, or boot/root disk combination. You
may need to build a static version of the hose program.
Put it on a floppy and mount it. Mount the partition to
become the new root as /mnt

And sit back while it copies. I
found that it was quite fast, compated too other file
transfer modes, such as FTP or SMB.

Make sure the uids and gids are set
to the right values. You might have to use a tar option.

You can also use netpipes to create a CD image
of your linux system, either for duplicating the system or as a
backup. Instead of untarring the result you write it to a file
on your CD burner. If your burner is a Windows machine then you
can use my winhose.exe to download it.
When you create the CD you can either create an .iso image or write
the tar file directly to the CD. If you do the later then you
will probably only be able to read it back from Linux which in most
cases is not a problem.

Using SSH

You can also copy files like this using ssh.
This might be a bit slower but you get the advantages of authentication
and encryption.

The destination machine only needs to be running
a ssh server. On the source machine/client, run the following command:

tar -cf - myfiles | ssh user@host "umask
000 ; tar -xpf -"

You could use use root@host but you have to make
sure that your have enabled root logins via ssh. It might be
worth enabling root logins for this procedure and then turning it back off
when you are finished. Obviously to create files as other users,
and to create device nodes etc. you must be root.

TODO: Is is possible to execute su on the remote
end before sending through the tar data?